This invention relates to a disposable pull-on undergarment such as a disposable diaper for absorption and containment of bodily wastes.
A disposable pull-on undergarment is well known, in which a liquid-absorbent core is disposed between a topsheet and a backsheet, a waist-opening is provided with an elastic member extending under tension along a peripheral edge thereof, a crotch region extending between front and rear waist regions is formed at its transversely opposite sides with leg-openings, respectively, and the respective leg-openings are provided along peripheral edges thereof with elastic members under tension.
Japanese Patent Application Disclosure Gazette (Kokai) No. Hei3-82467 discloses a disposable pull-on undergarment, in which respective leg-openings are provided with elastic means each comprising first and second elastic members. Respective intermediate portions of the first and second elastic members extend across a liquid-absorbent core in a crotch region. Lateral extensions of the first elastic member which are continuous with opposite ends of its intermediate portion extend substantially over front halves of the respective leg-openings' peripheral edges while lateral extensions of the second elastic member which are continuous with opposite ends of its intermediate portion extend substantially over rear halves of the respective leg-openings' peripheral edges. The first elastic member presents a stretch stress higher than a stretch stress presented by the second elastic member. In the known undergarment, the lateral extensions of the first elastic member extending substantially over the front halves of the leg-openings' peripheral edges can be put against the wearer's skin more tightly than the lateral extensions of the second elastic member. The intermediate portions of the first and second elastic members serve to lift the crotch region of the undergarment toward the wearer's skin.
The undergarment provided around the leg-openings with elastic members, a distance by which the elastic member extending in the rear waist region should be spaced from the opposite side edge of the absorbent core has usually been dimensioned to be larger than a distance by which the elastic member extending in the front waist region should be spaced from the side edges of the absorbent core. When the elastic member is relieved of the tension and the undergarment is left free, a contractile force of the elastic member extending in the front waist region forcibly contracts the absorbent core in the longitudinal direction. As a result, the absorbent core is apt to be creased.
The undergarment disclosed in the Japanese Patent Application Disclosure Gazette (Kokai) No. Hei3-82467 is arranged so that the first elastic member presents a relatively high stretch stress and therefore the portion of the absorbent core lying in the front waist region is significantly creased. Such portion of the absorbent core formed with creases has an apparent thickness larger than the remainder and inevitably becomes bulky. The partial bulkiness requires much labor and time for operation of packaging the undergarment one by one or a plurality of undergarments together because the partially bulky portions of the undergarment must be compressed during the operation of packaging the undergarment.